1. Field of the Invention
The present invention relates to a composite support frame structure for the construction of a seat and/or backrest of a seating structure and wherein the support frame is formed of a rigid continuous rod-like frame forming a closed loop and wherein a belt having the shape of a truncated sleeve is retained with the seating portion suspended in tension in such a way that a person in seating posture could not contact any rigid element. A tensile force is applied to the sleeve by the side members of the frame which are placed in compression when the sleeve is positioned over the frame. The invention also relates to the fabrication of a seat structure incorporating the rod-like composite support structure.
2. Description of Prior Art
It is common in the construction of chairs or other types of small seating structures to find support frames being constructed of rigid panels which are formed or molded and on which a padded composite structure is secured, such as a shaped foam padding, and a fabric positioned thereover and clamped to the panel. The foam padding is usually shaped to provide comfort for the user. However, often the ischium bone of a person seated on the cushion will feel pressure by the solid structure under the padding. Other seating structures are also known wherein peripheral tubular frames are provided and a plurality of bands, of stretchable material, is secured thereto, such as plastic bands, which extend laterally or in a woven fashion and spanning the tubular members to form a frame structure. It is also known to provide a peripheral frame structure which defines a seating portion and a backrest portion with a tension bar interposed inside the frame. A sleeve of fabric material is slid over the frame from one end and the tension bar places it in tension to form a chair frame. Such a structure is, for example, disclosed in U.S. Pat. No. 3,600,035 issued to George's Vondrejs. With such a structure, there may be provided a single sleeve or two sleeves, one for the backrest and the other for the seating portion of the frame. However, with these structures, it is necessary to use a tension bar secured within the frame whereby to maintain the frame expanded to apply tension to the belts once they are slid into position on the frame. Furthermore, in order for the sleeve to be maintained in position, it is necessary to secure these sleeves is to attachment structures which are secured to the frame, such as wooden brackets, and the sleeve stapled or otherwise secured to the bracket to prevent it from moving. Again, the ischium bone or the buttocks of a person seated on the cushioned frame might feel some of the frame structure.